Rolling electronic length measuring device

ABSTRACT

An electronic measuring device is disclosed which includes a pair of wheels connected to an axle that passes through a drive gear. The drive gear is enmeshed to a second gear which, in turn, is coaxially connected to an encoder disk. The encoder disk has spaced-apart fins around its outer periphery. As the wheels turn and the encoder disk rotates, the fins and openings between the fins pass between an emitter and a receiver. The emitter and receiver are linked to a controller which calculates the distance traversed by the wheels based upon the number of fins that pass between the emitter and receiver, or with an active counting system (ACS). The controller also includes functions to establish start and stop points for a measurement and an easy means for dividing a measured distance into equal parts or segments and a means for marking the boundary points that define the segments when the measuring device is rolled back across the measured distance. The device can be used on both planar and non-planar surfaces.

This application is a continuation application of and claims priority toU.S. patent application Ser. No. 10/894,277 filed on Jul. 19, 2004 nowU.S. Pat. No. 7,036,241, entitled “Rolling Electronic Length MeasuringDevice,” the entire disclosure of which is incorporated herein byreference.

TECHNICAL FIELD

This disclosure relates generally to measuring devices, such asmeasuring tapes. However, the disclosed device is an electronicmeasuring device that rolls along the surface to be measured.Accordingly, the device is suitable for non-planar surfaces includingcurved surfaces. The disclosed device provides an alternative tometallic coiled tape measuring devices, cloth or plastic measuring tapesand sonic or laser measuring devices.

BACKGROUND OF THE RELATED ART

One problem associated with conventional measuring devices such as tapemeasures, rulers, yard sticks or even sonic or laser type electronicdevices is that certain measurements are difficult to obtain.Specifically, accurately measuring the length of a curved or non-planarsurface with a metal tape measure is difficult. Further, cloth or fabrictape measures similar to the ones used by tailors are not convenient incertain environments, such as construction sites because they are noteasily retracted to a coiled position like the common metal tapemeasures. Electronic devices relying upon sonic or laser technology tomeasure distances are only suitable for straight measurements orline-of-site measurements.

Another problem associated with currently available length or distancemeasuring devices is that the manipulation of the obtained measurementmust be performed by the user with or without the use of a separatecalculator. For example, if a measured distance needs to be divided intoa number of equal segments, the user of a conventional tape measure mustfirst make the measurement, record the length, perform the requireddivision and then, using the tape measure, mark off the desiredsegments. This process is cumbersome and tedious and often results inerrors. Errors in such measurements the fields in carpentry or homeremodeling can be costly or damaging particularly if one or more holesare drilled in a wall or surface at one or more incorrect locations.

While traditional tape measures with a coiled measuring tape have beencombined with calculators, these devices have not been commerciallysuccessful because they fail to address the problem of measuring thedistance of a non-planar or irregular surface such as a curved wall.Further, the known combination calculator/tape measure devices merelycombine a calculator with a tape measure and do not provide the userwith any convenient means for dividing a measured distance into equallengths or segments and accurately marking those segments.

Accordingly, there is a need for an improved measuring device that canaccurately measure the length of a surface that is non-planar and thatfurther can easily and conveniently divide the measured length into oneor more equal segments and provide the user with a quick and easy systemto mark off the equal segments.

SUMMARY OF THE DISCLOSURE

An improved electronic measuring device is disclosed which can measurethe length or distance along almost any surface, including both planarand non-planar surfaces. In an embodiment, one disclosed devicecomprises at least one wheel for engaging or rolling along the surfaceto be measured. The wheel is mounted on an axle. The axle is coupled,either directly or indirectly, to an encoder disk so that rotation ofthe wheel results in rotation of the encoder disk.

In one embodiment, the encoder disk comprises a plurality ofcircumferentially spaced-apart opaque sections disposed betweentranslucent sections. The opaque and translucent sections (or the outerperiphery of the encoder disk) pass between an emitter and at least onereceiver as the encoder disk and wheel rotate. The emitter andreceiver(s) are linked to a controller. The controller computes thelength or distance traveled by the wheel based upon the number of opaquesections (or translucent sections) that pass between the emitter andreceiver during rotation of the wheel.

The encoder disk may be provided in a variety of forms. For example, theopaque sections may be fins and the translucent sections may be gaps oropenings between the fins. The encoder disk may be optically clear withspaced apart-opaque markings along its outer periphery that serve aslight-blocking sections with gaps or spaces of clear material disposedbetween the opaque markings. As another example, the encoder disk may bemade from an opaque material with though-holes disposed about its outerperiphery that allow light to pass through to the receiver(s) and theopaque material between the through-holes serves the purposed ofblocking light like the opaque sections or fins discussed above.

In a refinement, the axle passes through and is connected to a firstgear. The first gear is enmeshed with a second gear. The second gear iscoaxially connected to the encoder disk. In this embodiment, rotation ofthe wheel causes rotation of the axle thereby imparting rotation to thefirst gear, second gear and encoder disk.

Alternatively, the axle may be directly coupled to the encoder diskwithout a gear train coupling the axle to the encoder disk. If a geartrain is utilized, to prevent backlash when the directional movement ofthe device is quickly reversed, the axle or shaft supporting the secondgear and encoder disk may be loosely supported in a bearing and biasedtowards the first gear using a spring.

In a refinement, the at least one wheel comprises two wheels coaxiallyconnected together by the axle with the first gear disposed between thetwo wheels and mounted on the axle. By using two wheels, it is easierfor the user to roll the measuring device along a straight line.

In another refinement, the device comprises a display, such as a liquidcrystal display (LCD) or other type of display linked to the controllerfor displaying the distance traveled by the measuring wheel as computedby the controller.

In another refinement, the device further comprises a lower basestructure connected to an upper housing. The base has openings for theone or more wheels that roll along the surface to be measured. The baseis also connected to at least one bearing for rotatably supporting theaxle and at least one bearing for rotatably supporting the second gearand encoder disk. Of course, the bearings may also be connected to theupper housing. Also, the bearings may be molded as an integral part ofeither the upper housing or base.

In another refinement, the emitter and receiver are both mounted to afirst printed circuit board (PCB). The first PCB is linked to a secondPCB that is connected to and supports the controller and LCD.

Further, the second PCB may be linked to a plurality of control buttons.Each control button extending upward through openings disposed in theupper housing is linked to the controller to activate a program functionof the controller.

In another refinement, at least one of the control buttons is used toactivate a computation by the controller to account for the width of thehousing or the width of the measuring device.

In another refinement, at least one of the buttons is used to activate acomputation by the controller to divide the length previously measuredinto a plurality of equal segments. The segments may be defined by a“point” between adjacent segments. In such a refinement, as the deviceis rolled back across the previously measured distanced, the controllerprovides an indication when the device is approaching and traversing a“point.”

In another refinement, the segments are numbered and the number of thesegment being traversed is indicated on the display as the device ismoved back across the previously measured length. Further, in such arefinement, the display indicates when the device is approaching thenext segment so as to provide an early warning to the user as to howclose the device is to the next segment so that the user can be ready toplace a mark or other indicia on the surface at the designated “point.”

Further, the housing of the device may comprise two opposite side wallsthat are generally parallel to the axle that supports the one or morewheels. In an embodiment, each side wall is slidably connected to an endstop. Each end stop structure comprises a lower distal end having atapered point. Each end stop is movable between one or more lowerpositions where the tapered point can make an indentation or a markingon the surface being measured and an upper position where the taperedpoints are disposed above the surface being measured and therefore outof the way. It may also be preferable for the end stops to have a rangeof motion that extends below the surface being measures (or below thewheel or wheels that roll along the surface being measured) so that theend stop can be used to start a measurement at an end of a board orother structure.

Preferably, the end stops are biased into the upper position and arepressed downward by overcoming the bias to press the tapered pointagainst the surface being measured to mark one of the calculated“points” as discussed above or beginning and an ending points of ameasurement.

Also, each tapered point is preferably in vertical alignment with theouter surface of its respective side wall of the housing so that thetapered points can be accurately used to define the width of the housingwhich, in turn, can be easily accommodated for by the controller whenmaking a measurement. Further, in a preferred embodiment, when an endstop is extended downward beyond the surface being measured (i.e. pastthe wheels), the inside surface of the end stop is in vertical alignmentwith the outer surface of its respective side wall of the housing so theinside surface of the end stop can be used as an accurate start or stoppoint of a measurement.

For example, the user can press a control button to indicate to thecontroller which side wall of the housing is serving as a starting pointfor the measurement. After the device has been rolled across the surfaceto be measured, the user then may press a button to indicate to thecontroller which side of the device serves as the end point for themeasurement. If different side walls or sides of the device serve as thestarting or end points, the controller can easily accommodate for the“width” of the upper housing of the device by adding the width of thehousing to the computed length thereby providing for an accuratemeasurement.

Of course, there will be times when the width of the housing needs to besubtracted from the computed length or not taken into consideration atall.

In another refinement, the device includes a pair of guide rollers forstabilizing the device thereby providing a pair of measuring wheels anda pair of guide rollers.

In another refinement, the opaque and translucent sections of theencoder disk each have a uniform width and the receiver is a dualreceiver that comprises two spaced-apart receiving elements. Thereceiving elements are spaced-apart by a distance less than the uniformwidth of the translucent and/or opaque sections which thereby enablesthe controller to determine the direction of travel of the encoder diskand therefore the direction of travel of the measuring device.Preferably, the emitter is a light emitting diode (LED).

An improved method for measuring a length or a distance along a worksurface that may be planar or non-planar is also disclosed. The methodcomprises rolling a wheel of a measuring device as described above alongthe length or distance to be measured, computing the length or distancetraveled by the wheel by counting the number of opaque or translucentsections that pass between the emitter and the receiver as the wheel isrolled along the length or distance and determining a direction oftravel of the encoder disk and therefore the wheel by the order in whichthe receiving elements are shielded from light emitted by the emitter bythe passing opaque sections of the rotating encoder disk.

In a refinement, the method may also accommodate for the width of themeasuring device and the method may also include the option of dividingthe measured length into equal segments and enabling the user to retracethe length and easily mark off the equal segments at predetermined“points.”

Other features and advantages of the disclosed is devices and methodswill be apparent to those of ordinary skill in the art in view of thedetailed description provided below which is made with reference to theattached drawings provided in illustration of one preferred embodiment.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top perspective view of a measuring device made inaccordance with this disclosure;

FIG. 2 is an end view of the device shown in FIG. 1 with one of the endstops in a first lower position thereby enabling the tapered point toengage the surface being measured to provide a mark on the surface inalignment with the outermost surface of the side wall of the device;

FIG. 3 is another end view of the measuring device shown in FIGS. 1 and2 with one of the end stops in an second fully lowered position with aninner wall of the end stop being disposed below the surface beingmeasured and with the inner surface of the end stop being in alignmentwith an outermost surface of the side wall of the device therebyproviding a starting point or an end point for the length or distancebeing measured;

FIG. 4 is a partial sectional view of the device shown in FIGS. 1–3illustrating the slidable connection between the end stop and thehousing of the measuring device while the end stop is in its upper orretracted position;

FIGS. 5–7 provide an exploded view of the disclosed measuring devicewith FIG. 5 being a perspective view of the upper housing of themeasuring device shown in FIGS. 1–3;

FIG. 6 is a perspective view of the controller, control panel or controlbutton panel and a PCB of a disclosed measuring device;

FIG. 7 is a perspective view of the base structure, measuring wheels androtating components of a disclosed measuring;

FIG. 8A is an enlarged view of the components supported by the base asshown in FIG. 7;

FIG. 8B is an enlarged partial view of the emitter, receiver and encoderwheel components shown in FIG. 8A;

FIGS. 8C–8E are plan views of encoder disk designs that may beincorporated into the measuring device disclosed herein;

FIG. 9 is an illustration of the LCD of the disclosed device and a tableindicating which indicia will be disclosed on the LCD as the deviceapproaches and passes a “point” dividing equal segments of the measureddistance as computed by the controller at the command of the user;

FIG. 10 is a partial logic flow chart of the software stored on thecontroller shown in FIG. 6; and

FIG. 11 is another partial logic flow chart for the software stored onthe controller shown in FIG. 6.

DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS

FIG. 1 illustrates a measuring device 20 that includes an upper housing21 with an opening 22 for a display 23, preferably a LCD. The housing 21also includes a plurality of openings providing the user with access tocontrol buttons 24, 25, 26, 27 and 28. Further, the device 20 alsoincludes end stops 31, 32 disposed in side walls 33, 34 respectively forproviding convenient start and stop points for a measurement and formarking the surface being measured as described in greater detail below.

Turning to FIG. 2, the rolling device 20 includes a measuring wheel 35(in this case a pair of measuring wheels 35 as shown in FIG. 7) thatengages the surface to be measured. In a preferred embodiment, a pair ofguide rollers shown at 36 is also provided. Preferably, two wheels 35are utilized as the use of two wheels 35 makes it easier for the user toroll the device 20 in a straight line.

In FIG. 2, the end stop 31 has been pushed downward, overcoming the biasof a spring (See 47 in FIG. 4) so that a tapered point 37 disposed at alower distal end 38 of the end stop 31 engages the surface 39 beingmeasured. In the “first” lower position shown in FIG. 2 (or “second”lower position shown FIG. 3 and discussed below), the end stop 31 can beused as either a start or a stop point for a measurement. The taperedpoint can also be used to make an indentation in the surface 39 and isparticularly useful for sheet rock, drywall and wood.

In FIG. 3, the end stop 31 has been lowered to the end if its range asdiscussed below with respect to FIG. 4 so that an inner surface 41 ofthe end stop 31 engages an end wall 42 of the surface 39 being measured.In both FIGS. 2 and 3, the end stop 31 (and the same applies for the endstop 32) serves as an accurate starting or finishing for a measurement.Specifically, in the “first” lower position shown in FIG. 2, the taperedpoint 37 is in vertical alignment with an outermost portion of the sidewall 33 of the upper housing 21. Thus, in the position in FIG. 2, thetapered point 37 can serve as a convenient start or finishing point forthe measurement. Similarly, in “second” or “lowermost” position shown inFIG. 3, the inner surface 41 of the end stop 31 is also in verticalalignment with an outermost portion of the sidewall 33 thereby alsoserving as a convenient starting or stopping point for a measurement.

The end stop 31 is shown in greater detail in FIG. 4. Specifically, theend stop 31 includes an upper thumb or finger grip 44 connected to avertical wall 45 that terminates in the distal end 38 which features thetapered point 37. The end stop 31 is biased into an upper position shownin FIG. 4 by the spring 47. The vertical portion 45 of the end stop 31is connected to opposing side walls, one of which is shown at 46. Eachside wall 46 of each end stop 31 (and 32) is connected to two pawlsshown at 49 and 51. The pawls 49, 51 each ride in elongated slots 52, 53respectively that are disposed in the vertical wall shown at 54 in FIG.4.

In FIG. 4, the end stop 31 shown in its upper or retracted positionunder the bias of the spring 47. The pawls 49, 51 are disposed at theupper ends 52 a, 53 a of the slots 52, 53 respectively. In first lowerposition shown in FIG. 2, the pawls 49, 51 are between the upper (52 a,53 a) and lower (52 b, 53 b) ends their respective slots 52, 53 and theorientation of the slots 52, 53 in the wall 54 maintain the taperedpoint 37 in vertical alignment with an outermost portion of the sidewall33 so that the mark or indentation made by the point 37 on the surface39 is accurately aligned with the sidewall 33 of the device 20.

As the end stop 31 is pushed further downward towards the fully extendedposition shown in FIG. 3, the inner surface 41 of the end stop 31, inturn, moves into vertical alignment with an outermost portion of theside wall 33 as shown in FIG. 3 when the pawls 49, 51 are disposed atthe lower ends 52 b, 53 b of their respective slots 52, 53. The slots52, 53 are disposed within a wall structure shown at 54 that may beformed from the base 50 as shown in FIG. 7 or which may be a moldedportion of the upper housing 21 or a separate component altogether. Asshown in FIGS. 7 and 8, each end stop 31, 32 includes a pair ofsidewalls 46 and two sets of pawls 49, 51 and the base 50 or housing 21provides two pairs of slots 52, 53 for each end stop 31, 32.

Turning to FIGS. 5–7, the upper housing 21 serves as an enclosure for aPCB 55 which is connected to and supports the button pad 56, controller57 and LCD 23. The PCB 55 is connected electrically to another PCB 58which is mounted to the base 50. The PCB 58 is connected to and supportsthe emitter 59 and dual receiver 61. The emitter 59 directs lighttowards the receiver 61. Preferably, for reasons discussed below, thereceiver 61 is a dual receiver with two separate receiving elements.

Referring to FIGS. 7 and 8A–8E, a finned encoder disk or wheel 62rotates between the emitter 59 and the receiver 61. The encoder disk 62as shown in FIGS. 7, 8A and 8C includes a plurality of fins or markers63 that are spaced apart with uniform gaps or openings 64 disposedbetween the fins 63. The encoder disk 62 also includes a hub 70 whichaccepts an axle 78 (see FIGS. 8C–8E) for coaxially connecting the disk62 to the gear 65 (see FIG. 8A).

The gaps or openings 64 of the disk 62 (FIG. 8C) may also be in the formof circumferentially spaced-apart through-holes 64 a as shown in thedisk 62 a of FIG. 8D. Still referring to FIG. 8D, the solid material 63a disposed between such through-holes 64 a serve the function ofblocking light like the fins 63 as shown in FIGS. 7, 8A and 8C. Anotheralternative is shown in FIG. 8E where the disk 62 b is made of anoptically clear material with circumferentially spaced-apart opaquemarkings 63 b disposed between clear light transmitting openings 64 b.In generally, the encoder disk 62 includes a plurality ofcircumferentially space-apart opaque sections 63, 63 a, 63 b disposedbetween a plurality of circumferentially spaced-apart translucent ortransparent sections 64, 64 a, 64 b. Other encoder disk 62 designs willbe apparent to those skilled in the art.

In the embodiment shown in FIGS. 7 and 8A, the encoder disk 62 iscoaxially connected to a splined shaft or gear 65 by the axle 78 (seeFIGS. 8C–8E). The gear 65 is enmeshed with a drive gear 66 mounted onthe axle 67. The axle 78 passing through the encoder disk 62 and gear 65is supported at either end (not shown) by the bearings shown at 68 a, 68b. Preferably, the bearing 68 b has an elliptical or non-circular holefor loosely accommodating and supporting the axle 78 so that one end ofthe axle 78 can move in an limited manner against the bias of the spring71 to prevent backlash when the direction of the travel of the device 20is quickly reversed.

Thus, to maintain a proper coupling between the. gears 65 and 66, thespring 71 may be used to bias the gear 65 towards the drive gear 66.Again, it will be noted that the encoder disk 62 can be directly coupledto or mounted on the axle 67. The disclosed gear train 66, 65 has beenemployed to conserve space within the housing 21.

Preferably, the device 20 is battery operated and a battery housing isshown at 72. A plurality of support posts are shown at 73 and are usedto receive a screw from the underside of the base 50 to connect to base50 to the upper housing 21. The PCB 55 may be secured to the undersideof the upper housing 21 or may be mounted to the base member 50. In anyevent, the PCB 55 is electrically linked to PCB 58 or separately linkedto the emitter 59 and receiver 61.

Therefore, as the device 20 is rolled across the surface 39 to bemeasured, the wheels 35 roll across the surface 39. The wheels 35 arepreferably coated with rubber, thermoplastic rubber, or another similarmaterial. As the wheels 35 rotate, the drive gear 66 rotates and, inturn, rotates the gear or splined shaft 65 which, in turn, rotates theencoder disk 62. When the device 20 has been turned on, light is emittedfrom the emitter 59 and directed towards the receiver 61. Preferably,the receiver 61 includes a pair of receiving elements. The controller 57counts the number of fins 63 (or openings 64) that pass between theemitter 59 and receiver 61 as the fins 63 block the transmission oflight between the emitter 59 and receiving elements disposed on thereceiver 61. By counting the number of fins 63 that pass between theemitter 59 and receiver 61 (or, by counting the number of openings 64that pass between the emitter 59 and receiver 61), the controller 57 cancompute the distance traveled by the wheels 35. Further, by using a dualreceiver 61 with two receiving elements 61 a, 61 b, the controller 57can determine which direction the device 20 is being moved by the orderin which light from the LED element 59 a is blocked from the spacedapart receiving elements 61 a, 61 b by the passing fins 63.

Further, the controller 57 of the device 20 can accommodate for thewidth of the device 20 or the distance between the side walls 33 and 34as follows. By pressing one of the buttons, in this example, the button24, the user indicates to the controller 57 that the side 33 with theend stop 31 of the device 20 is the active measuring side or edge. Atthe conclusion of the distance measurement, the user then may keep theside 33 as the active measuring side or, in the event, the device 20engages a vertical wall, the user may then press another button, such asthe button 25, to indicate to the controller 57 that the opposite side34 is now the active measuring side. The controller will then add thewidth of the device between the sides 33 and 34 to the length measured.

Further, the controller 57 is preferably programmed to divide themeasured distance into a number of equal segments or points. The button27 can be used for this purpose. In a preferred embodiment, if adistance is to be divided by four equal segments or four points, thebutton 27 is pressed four times. If the distance is to be divided by tenequal segments, the button 27 is pressed ten times. The button 28 mayused as a clear or zero button and the button 26 may be used as acombination start/stop button as well as a power-on button. Theconfiguration and function assignments of the buttons may vary greatlyand only one example is provided here. Thus, the controller 57 iscapable of performing various calculations.

Turning to FIG. 9, the display 23 is shown when the user has selectedthe “points divide” option by repeatedly depressing the button 27. Whenthe device 20 is in this mode, the display 23 will read POINTS at thebottom left. The size of the equal segments determines which arrows 75a–75 d or 76 a–76 d will be shown for each distance range away from thepoint. For equal segments that are greater than two inches the columnson the left of the chart 77 will be used, and for equal segments betweenone and two inched the columns on the right of the chart 77 will beused. The center of chart 77 shows the state of each arrow within thatrange on the left or right. “F” indicates that the element is flashingand “O” indicates it is off. If the device 20 is approaching the pointfrom the left, then the left arrows shown at 75 a–75 d will begin toflash as the device 20 moves closer to the point. If the device isapproaching from the right, then the right arrows shown at 76 a–76 dwill begin flashing as the device moves closer to the point. When thedevice 20 is within 0.06″ of the point, then all of the arrows 75 a–75d, 76 a–76 d will be turned off and the word POINT will flash inaddition to an optional audible tone. During the approach and on thepoint, the display 23 will also indicate which point the device is near.For example, you may be approaching “1 OF 3 POINTS”, whereas the POINTSwill be on display throughout points mode. The images, distances andmethod for indicating the approach of each point can vary greatly.

FIGS. 10 and 11 illustrate logic flow charts for software that may bestored in the memory of the controller 57. The flow charts and logicshown in FIGS. 10–11 and merely one example of the many types ofprograms that could be used. At 100, the user decides to take ameasurement using the device 20, which is turned off or in the powerdown mode as shown at 101 and the user presses the power on button 26 at102 to power up the device at 103. At 104, the LCD indicates the laststatus and units of measurement data. At 105, the controller 57indicates the current active measuring side, i.e., the left side 34 orthe right side 33 on the LCD 23. At this point, to begin a newmeasurement, the user may press the clear button 28 at 106 to clear thepreviously stored data at 107 to redisplay the cleared status at 104 andcurrent active edge at 105 as shown by the loop 106-107-104-105-106. At108, the user may then change the units of measurement at 108 bysimultaneously pressing and holding the buttons 24 and 25 down for fiveseconds whereby the controller enters the loop 108-109-104-105-108 asshown in FIG. 10. To use the left side 34 of the device 20 as the activemeasuring side and the controller determines at 111 if this would be achange from using the right side 33 as the active measuring side and, ifso, would subtract the width of the device at 112 and the display 23would indicate that the left side 34 is the active measuring side at113. Similarly, if the right side 33 is selected as the active measuringedge at 114 and the controller 57 determines that this would be a changeat 115, the controller 57 adds the width of the device to themeasurement at 116 and makes an appropriate indication on the display 23at 117. To begin counting, the user then presses the start/stop button26 again at 118 and, if the controller 57 determines that the device isnot already active at 119, the controller 57 changes the active countingsystem (ACS) to active at 120 to begin taking measurement data. If thesystem is in the active counting mode, the controller 57 then changesthe system to the inactive counting at 121.

Then, the controller again passes through the loop104-105-106-108-110-114-118 and, if the user is beginning to take aninitial measurement, the user will not press the points divide button 27at 122 but, instead, will begin rolling the device whereby thecontroller will detect movement of the wheels 35 by way of the mechanismdescribed in FIGS. 7 and 8 above to activate the ACS system. In anembodiment, the speed limit is 10 feet per second and the speed limit ischecked at 124 (and an error signal can be generated at 124 a) beforethe active status is confirmed at 125 and the measurement begins at 126and the controller 57 continuously displays the measurement data on thescreen 23 at 127 before the user stops the device at 128. Again,proceeding through the loop shown at 104-105-106-108, the user then maychange the active measuring edge of the device at either 110 or 114 toeither result in an addition or subtraction of the width of the device20. If no such change is made, and the measurement has been completed,the user may then press the points button 27 at 122.

Turning from 122 a at FIG. 10 to 122 a at FIG. 11, the controller 57confirms the active mode status of the device at 131 and, if the deviceis still in an active mode, the controller 57 will reject the pointsmode. The controller will then confirm that the measurement is less thanone inch at step 132 and, if it is, the controller 57 will reject thepoints mode if the measurement is more than one inch, the controller 57proceeds to 133 and initiates the display of a point number “1” on thedisplay 23 as the points button 27 has been pressed only once. Repeatedpressing of the points button 27 at 134 sends the system into the loop134-135-133-134 until the desired number of points or segments isarrived at. The box 135 indicates that the maximum number of allowablepoints is 10 but those of ordinary skill in the art will realize thatthis number is flexible and will depend upon the particular applicationthat the device 20 is intended for. That is, more or fewer than tenpoints may be desired.

When the desired number of points or segments are entered, the userpresses the start/stop button 26 at 136 which initiates the dynamicmeasurement and the arrow display at 137 that is illustrated anddiscussed above at FIG. 9. At this point, to mark off the points alongthe path just measured, the user does not roll the device forward atstep 138 but, instead, begins to roll the device backward at step 142retracing the path just measured. Continued forward movement of thedevice at 138 will result in a continued display of the measurement dataat step 140.

To reach a target point by rolling the device 20 backwards as shown atstep 141, the controller 57 continually checks to make sure that thedevice has not rolled backward past the zero point at 142 (where if thedevice has rolled past the zero point, the display continues to indicatea zero value at 143), and assuming two minutes of an action have nottaken place at 144, and assuming the user has not pressed clear at 145,the bar graph (or arrows display) will indicate proximity to the firsttarget point and when it is reached at 141, optionally, an audio signalis produced at 146 and the icon point number flashes on the screen at147. As the user continues to move the device 20 backwards retracing thejust-measured path, and leaves a target point at 148, the target pointicon stops blinking at 149 and the loop137-138-142-144-145-141-146-147-148-149 is repeated for the next targetpoint. When the device rolls back to the initial starting point andbegins to exceed the “0” point, the measurement is complete andeventually two minutes of an action will occur and the logic returns todata FIG. 10 at step 151 or 152. Pressing clear at step 153 will convertthe controller 57 to distance mode at 154 to begin a new measurement at155 returning to the logic flow illustrated in FIG. 10. Again, twominutes of no action (see step 156) will result in the display 23 beingturned off at 157.

Accordingly, an improved measuring device 20 is disclosed which canaccurately measure distances or lengths along planar or non-planarsurfaces easily and conveniently. The device 20 is highly accurate byway of its employment of the end stops 31, 32. The device 20 may easilydivide a measured length or distance or equal segments which may then beeasily marked with the end stops 31, 32, and both visual and audibleindications are provided when the device retraces a measure distance anddesignated points are approached and passed.

1. An electronic measuring device for measuring length or distance alonga surface, the device comprising: a housing; at least one wheel forengaging and rolling on the surface, the wheel being mounted on an axle,the axle being coupled to an encoder disk, the encoder disk comprising aplurality of circumferentially spaced-apart opaque sections withtranslucent sections disposed the opaque sections, the opaque sectionsand translucent sections of the encoder disk passing between an emitterand a receiver when the wheel rotates, the emitter and receiver beinglinked to a controller, the controller computing the length or distancetraveled by the wheel by counting the number of opaque sections ortranslucent sections that pass between the emitter and receiver; and atleast one control button on the housing, the at least on control buttonconnected to the controller, wherein the at least one control buttonselects a start measurement point and an end measurement point, thestart measurement point and the end measurement point being selectablerelative to a position on the housing.
 2. The measuring device of claim1 wherein the axle passes through and is connected to a first gear, thefirst gear is enmeshed with a second gear, and the second gear iscoaxially connected to the encoder disk.
 3. The measuring device ofclaim 2 wherein the at least one wheel comprises two wheels coaxiallyconnected by the axle with the first gear disposed therebetween.
 4. Themeasuring device of claim 1 further comprising a display linked to thecontroller for displaying the distance traveled by the at least onewheel and computed by the controller.
 5. The measuring device of claim 1wherein the emitter and receiver are both mounted to a first printedcircuit board, the first printed circuit board being linked to a secondprinted circuit board that is connected to and supports the controller.6. The measuring device of claim 5 wherein the second printed circuitboard is linked to a plurality of control buttons.
 7. The measuringdevice of claim 6 wherein at least one of the buttons is used toactivate a computation by the controller to account for a width of ahousing that encloses the controller, encoder disk, emitter, andtransmitter.
 8. The measuring device of claim 7 wherein the housingcomprises two opposite side walls generally parallel to the axle thatdefine a width of the device, each side wall being slidably connected toan end stop, each end stop comprising an marking element for marking thesurface being measured at a point in vertical alignment with the sidewall of the housing to which the end stop is connected.
 9. The measuringdevice of claim 8 wherein each end stop also comprises an inner surfacethat is in alignment with the outer surface of its respective side wallwhen the distal end of the end stop is moved to a position below orbeyond the surface being measured.
 10. The measuring device of claim 1wherein the opaque sections of the encoder disk are fins and thetranslucent sections of the encoder disk are gaps or openings betweenthe fins.
 11. The measuring device of claim 1 wherein the axle isconnected to two wheels that extend through openings in a bottom basepanel and the device further comprises a pair of guide rollers rotatablyconnected to a base panel.
 12. The measuring device of claim 1 whereinthe translucent sections and opaque sections of the encoder disk have auniform width, and wherein the receiver comprises two spaced-apartreceiving elements, the receiving elements being spaced apart by adistance less than the uniform width of said translucent and opaquesections and the controller determining the direction of travel of theencoder disk.
 13. An electronic measuring device for measuring length ordistance along a surface, the device comprising: at least one wheel forengaging and rolling on the surface, the wheel being mounted on an axle,the axle being coupled to an encoder disk, the encoder disk comprising aplurality of circumferentially spaced-apart opaque sections withtranslucent sections disposed the opaque sections, the opaque sectionsand translucent sections of the encoder disk passing between an emitterand a receiver when the wheel rotates, the emitter and receiver beinglinked to a controller, the controller computing the length or distancetraveled by the wheel by counting the number of opaque sections ortranslucent sections that pass between the emitter and receiver, whereinthe emitter and receiver are both mounted to a first printed circuitboard, the first printed circuit board being linked to a second printedcircuit board that is connected to and supports the controller, whereinthe second printed circuit board is linked to a plurality of controlbuttons, wherein at least one of the buttons is used to activate acomputation by the controller to divide the length or distancepreviously computed by the controller into the plurality of segments,wherein as the device is rolled back across the previously measuredlength or distance, the controller provides an indication when thedevice is traversing between one segment and a succeeding segment. 14.The measuring device of claim 13 further comprising a display linked tothe controller wherein the indication is provided on the display bynumbering the segments and indicating which numbered segment the deviceis traversing at any time during as the device is rolled across themeasured length or distance a second time and the controller has dividedthe computed distance into a number of segments.
 15. An electronicmeasuring device for measuring length or distance along a surface, thedevice comprising: a pair of wheels for engaging and rolling on thesurface, the wheels being mounted on an axle, the axle being coupled toan encoder disk, the encoder disk comprising a plurality of uniformspaced-apart circumferentially opaque sections with uniform translucentsections disposed between said opaque sections, the encoder disk passingbetween an emitter and a receiver comprising two spaced-apart receivingelements, the emitter emitting light towards the receiving elements thatis blocked by the opaque sections but allowed to reach the receivingelements by the translucent sections as the encoder disk rotates, theemitter and receiver being linked to a controller, the controllercomputing the length or distance traveled by the wheel by counting thenumber of opaque sections that pass between the emitter and receiver,the controller determining the direction of travel of the encoder diskand therefore the device by the order in which the receiving elementsare shielded from light emitted by the emitter by the opaque sections ofthe encoder disk, the controller being linked to a display fordisplaying the distance and direction traveled by the wheels andcomputed by the controllers, wherein the controller divides the lengthor distance traveled into a plurality of segments, each segment beingseparated from another segment by a point, the controller providing anindication that the device is approaching the point.
 16. The measuringdevice of claim 15 wherein the axle passes through and is connected to afirst gear, the first gear being enmeshed with a second gear, the secondgear being coaxially connected to the encoder disk.
 17. The measuringdevice of claim 15 wherein the emitter and receiver are both mounted toa first printed circuit board, the first printed circuit board beinglinked to a second printed circuit board that is connected to andsupports the controller and the display.
 18. The measuring device ofclaim 17 further comprising a housing having a plurality of openingstherein, one of the openings framing the display and other openings inthe housing providing access to a plurality of control buttons.
 19. Themeasuring device of claim 18 wherein at least one of the buttons is usedto activate a computation by the controller to account for a width ofthe housing.
 20. The measuring device of claim 17 further comprising anenclosing housing with two opposite side walls generally parallel to theaxle, each side wall being slidably connected to an end stop, each endstop comprising a lower distal end having a marking element that is inalignment with an outer surface its respective side wall when the endstop has been moved to a position where the marking element is inengagement with the surface being measured, and each end stop alsocomprising an inner surface that is in alignment with the outer surfaceof its respective side wall when the distal end of the end stop isdisposed below or beyond the surface being measured.
 21. An electronicmeasuring device for measuring length or distance along a surface, thedevice comprising: a pair of wheels for engaging and rolling on thesurface, the wheels being mounted on an axle, the axle being coupled toan encoder disk, the encoder disk comprising a plurality of uniformspaced-apart circumferential opaque sections with uniform translucentsections disposed between said opaque sections, the encoder disk passingbetween an emitter and a receiver comprising two spaced-apart receivingelements, the emitter emitting light towards the receiving elements thatis blocked by the opaque sections but allowed to reach the receivingelements by the translucent sections as the encoder disk rotates, theemitter and receiver being linked to a controller, the controllercomputing the length or distance traveled by the wheel by counting thenumber of opaque sections that pass between the emitter and receiver,the controller determining the direction of travel of the encoder diskand therefore the device by the order in which the receiving elementsare shielded from light emitted by the emitter by the opaque sections ofthe encoder disk, the controller being linked to a display fordisplaying the distance and direction traveled by the wheels andcomputed by the controller, a housing having a plurality of openingstherein, one of the openings framing the display and other openings inthe housing providing access to a plurality of control buttons, whereinthe emitter and receiver are both mounted to a first printed circuitboard, the first printed circuit board being linked to a second printedcircuit board that is connected to and supports the controller and thedisplay, wherein at least one of the buttons is used to activate acomputation by the controller to divide a length or distance previouslycomputed by the controller into a plurality of segments, wherein as thedevice is rolled back across the previously computed distance, thedisplay indicates when the device is traversing between one segment anda next segment.
 22. The measuring device of claim 21 wherein theindication is provided on the display by numbering the segments andindicating which numbered segment the device is traversing at any timeduring as the device is rolled across the measured distance a secondtime and the controller has divided the computed distance into a numberof segments.
 23. A method for measuring a length of or a distance alonga work surface, the method comprising: selecting a start measuringpoint, rolling a wheel of a measuring device along the length ordistance to be measured, the wheel being coaxially connected to a firstgear that is enmeshed with a second gear, the second gear beingcoaxially connected to an encoder disk, the encoder disk comprising aplurality of spaced-apart circumferential opaque sections withtranslucent sections between said opaque sections, the opaque sectionsand translucent sections being of an equal circumferential width, theopaque sections and translucent sections between the opaque sections ofthe encoder disk passing between an emitter and a receiver, the emitteremitting light directed to the receiver, the receiver comprising twospaced apart receiving elements, selecting a stop measuring point,computing the length or distance traveled by the wheel by counting thenumber of opaque sections that pass between the emitter and the receiveras the wheel is rolled along the length or distance being measured,determining a direction of travel of the encoder disk and therefore thewheel by the order in which the receiving elements are shielded from thelight emitted by the emitter by the passing opaque sections of therotating encoder disk, wherein the start and stop measuring points areselectable relative to a position on a device housing.
 24. The method ofclaim 23 further comprising accounting for a width of a housing thatencloses the wheel, gears and encoder disk.
 25. The method of claim 24further comprising dividing the measured length into a number of equalsegments, and assigning numbers to the segments.
 26. An electronicmeasuring device for measuring length or distance along a surface, thedevice comprising: at least one wheel assembly for engaging and rollingon the surface, the wheel assembly comprising an encoder, the encodercomprising a plurality of circumferentially spaced-apart markers, theencoder passing between an emitter and a receiver when the wheelrotates, the emitter and receiver being linked to a controller, thecontroller computing the length or distance traveled by the wheel bycounting the number of markers that pass between the emitter andreceiver, wherein start and stop measuring points are selectablerelative to a position on a housing of the electronic measuring deviceand the controller divides the length or distance traveled into aplurality of segments and provides an indication that the electronicmeasuring device is approaching a transition from one segment to anothersegment.
 27. The measuring device of claim 26 further comprising: ashaft on which the wheel is mounted, the shaft passing through and beingconnected to a first gear, the first gear being enmeshed with a secondgear, and the second gear being coaxially connected to the encoder disk.28. The measuring device of claim 27 wherein the at least one wheelcomprises two wheels coaxially connected by the shaft with the firstgear disposed therebetween.
 29. The measuring device of claim 26 furthercomprising a display linked to the controller for displaying thedistance traveled by the at least one wheel and computed by thecontroller.
 30. The measuring device of claim 26 wherein the emitter andreceiver are both mounted to a first printed circuit board, the firstprinted circuit board being linked to a second printed circuit boardthat is connected to and supports the controller.
 31. The measuringdevice of claim 30 wherein the second printed circuit board is linked toa plurality of control buttons.
 32. The measuring device of claim 31wherein at least one of the buttons is used to activate a computation bythe controller to account for a width of a housing that encloses thecontroller, encoder, disk, emitter, and transmitter.
 33. The measuringdevice of claim 26 wherein the encoder is a disk and the markers arecircumferential fins with gaps or openings disposed between the fins.34. The measuring device of claim 26 wherein the shaft is connected totwo wheels that extend through openings in a bottom base panel and thedevice further comprises a pair of guide rollers rotatably connected toa base panel.
 35. The measuring device of claim 26 wherein the markersof the encoder disk have a uniform width, and wherein the receivercomprises two spaced-apart receiving elements, the receiving elementsbeing spaced apart by a distance less than the uniform width of saidmarkers and the controller determining the direction of travel of theencoder disk.
 36. The measuring device of claim 35 wherein thecontroller performs calculation functions.
 37. An electronic measuringdevice for measuring length or distance along a surface, the devicecomprising: at least one wheel for engaging and rolling on the surface,the wheel being coupled to an encoder disk, the encoder disk comprisinga plurality of uniform spaced-apart circumferential opaque sections withuniform translucent sections disposed between said opaque sections, theencoder disk passing between an emitter and a receiver, the emitteremitting light towards the receiving elements that is blocked by theopaque sections but allowed to reach the receiver by the translucentsections as the encoder disk rotates, the emitter and receiver beinglinked to a controller, the controller computing the length or distancetraveled by the wheel by counting the number of opaque sections thatpass between the emitter and receiver, the controller being linked to adisplay for displaying the distance and direction traveled by the wheelsand computed by the controller, wherein start and stop measuring pointsare selectable relative to a position on a housing of the electronicmeasuring device and the controller divides the length or distancetraveled into a plurality of segments and provides an indication thatthe electronic measuring device is approaching a transition from onesegment to another segment.
 38. The measuring device of claim 37 whereinthe at least one wheel comprises two wheels mounted on an axle, the axlepassing through and being connected to a first gear, the first gearbeing enmeshed with a second gear, the second gear being coaxiallyconnected to the encoder disk.
 39. The measuring device of claim 37wherein the emitter and receiver are both mounted to a first printedcircuit board, the first printed circuit board being linked to a secondprinted circuit board that is connected to and supports the controllerand the display.
 40. The measuring device of claim 37 further comprisinga housing having a plurality of openings therein, one of the openingsframing the display and other openings in the housing providing accessto a plurality of control buttons.
 41. The measuring device of claim 40wherein at least one of the buttons is used to activate a computation bythe controller to account for a width of the housing.
 42. The measuringdevice of claim 37 wherein the receiver comprises two spaced apartreceiving elements, and the controller determining the direction oftravel of the encoder disk and therefore the device by the order inwhich the receiving elements are shielded from light emitted by theemitter by the opaque sections of the encoder disk.
 43. A method formeasuring a length of or a distance along a work surface, the methodcomprising: rolling a wheel of a measuring device along the length ordistance to be measured, the wheel being coupled to an encoder, theencoder comprising a plurality of spaced-apart circumferential markerswith spaces between said markers, the markers and spaces being of anequal circumferential width, the markers and spaces between the markersof the encoder passing between an emitter and a receiver, the emitteremitting light directed to the receiver, the receiver comprising twospaced apart receiving elements, computing the length or distancetraveled by the wheel by counting the number of markers that passbetween the emitter and the receiver as the wheel is rolled along thelength or distance being measured, determining a direction of travel ofthe encoder and therefore the wheel by the order in which the receivingelements are shielded from the light emitted by the emitter by thepassing markers of the encoder, wherein start and stop measuring pointsare selectable relative to a position on a housing of the electronicmeasuring device and the controller divides the length or distancetraveled into a plurality of segments and provides an indication thatthe electronic measuring device is approaching a transition from onesegment to another segment.
 44. The method of claim 43 furthercomprising accounting for a width of a housing that encloses theencoder.